Mountain View Voice

Opinion - December 14, 2012

Viewpoint: Odd results of TCE cancer impact study

The ongoing saga of how city residents cope with a plume of the toxic chemical TCE that flows beneath their homes took another turn last week when the Greater Bay Area Cancer Registry released data that shows nearly twice as many residents of the impacted area have contracted non-Hodgkin Lymphoma than expected.

But the survey results, compiled from 1988 to 2010 data, have some flaws, including the lack of information about exactly where the lymphoma victims live. No addresses were included in the study results of northeastern Mountain View released by the cancer registry. Instead, the general location was said to be roughly east of Shoreline Boulevard, north of Central Expressway and south of Highway 101, a slightly larger area than the so-called MEW area (Middlefield Road, Ellis Avenue and Whisman Road), long identified as the location of the primary TCE (Trichloroethylene) plume.

Given the seriousness of the study's results, which show 31 cases of lymphoma rather than the 17 cases expected between 1996 and 2005, residents of the area have a right to know specifically where spikes in the disease are located, even if scientists say the information is not strong enough to warrant concern. For example, just a description of a numbered block of a street would help residents know whether they are in a "hot" zone or not.

An official from the Cancer Registry said the spike in NHL was "not a conventional true cancer cluster." When asked if residents should be concerned if they lived in the area, he said, "Based on our best assessments, not any more than anybody else in the area."

The scientists based their conclusion, at least in part, on the finding that unlike the incidence of NHL, liver and kidney cancer were average. They attributed the high numbers of lymphoma found to a small sample. Given the size of the sample, "the statistics can bounce around wildly, and it's difficult to pin down significance," the official said.

We hope the mixed test results do not discourage the Cancer Registry from continuing to monitor residents whose homes are over or near the toxic TCE plume. Even more important is for the cancer registry to continue its studies of those who live above or near the city's TCE plume, to see if more impact can be found. EPA and other agencies that keep track of the impact this cancer-causing chemical have done a good job of tracking the elusive underground trail of TCE. Much more is known today than even five years ago.

But the search for dangerous levels of TCE vapors that come up from the plume, primarily the responsibility of the polluters, has been too slow or inadequate, especially at Moffett Field, where the Navy is the responsible party. (The Navy is not responsible for the plumes near the area studied. Several companies are, including Fairchild Semiconductor, GTE and Intel.) The Navy is responsible for cleaning up and keeping those impacted informed about the progress in finding where the TCE plumes are located and, more importantly, whether the danger has receded.

Luckily, the contaminated aquifers that carry TCE have not been tapped for drinking water for years, so no one has become ill from ingesting the water. And in recent history, new construction in the affected area has had to conform to building regulations that included laying down a barrier in building basements to stop the underground plumes from venting into homes or businesses.

Whisman Road resident Jane Horton, who owns one of the few homes where unsafe levels of TCE gas has been found, still suspects there is a connection between the cancer spike and the chemical. Her residence on Whisman Road is not too far from where an "air stripper" on Walker Drive was used to pump the toxic chemical to the surface where it was vented in the open air.

Horton believes more tests should be conducted to see if there is higher incidence of other types of disease beyond kidney and liver cancer, which were found to be at normal levels in the area. We think Horton has a good point. In many ways the threat from the TCE plume has receded, but whether the high incidence of lymphoma was an outlier of just one form of cancer, or the harbinger of other cancer outbreaks, is a question that should be answered for all residents of this impacted area. A study that leaves such questions unanswered is not enough.